The present invention relates to an oligomer including a nitrogen functionality and at least one ethylenic unsaturation. In particular, this oligomer has a nitrogen-functionality at one end of the oligomer, referred to herein as a semi-telechelic nitrogen-functionality, and at least one ethylenic unsaturation pendant to the oligomer backbone. Further, this invention relates to methods of preparing the oligomer.
U.S. Pat. No. 3,914,165 to Gaske discloses radiation curable amine containing monomers based on multifunctional acrylates which are partially functionalized with diethyl amine. Gaske discloses that these monomers are useful as amine synergists which are oxygen scavengers used to overcome the inhibiting effects of oxygen on the cure rate of radiation curable materials. Gaske exemplifies the use of these monomers in coatings such as pigmented inks and showed that formulations containing these monomers readily cured in the presence of oxygen. In xe2x80x9cChemistry and Technology of UV and EB Formulation for Coatings, Inks and Paintsxe2x80x9d, Volume II, edited by G. Webster, John Wiley and Sons, Ltd., New York, N.Y., it is also disclosed that amine acrylates such as the monomers of Gaske may promote pigment wetting. However, one deficiency with the nitrogen-functional monomers of Gaske is that in the process to prepare these monomers, the addition of the amines to the multifunctional acrylates is a random process which leads to a mixture of monomers including monomers with more than one amine functionality and monomers without an amine functionality.
In the present invention, a new class of nitrogen-functional, ethylenically unsaturated oligomers is provided which are useful as polymerizable dispersants and for radiation curable formulations. In particular, the oligomers of this invention have a single nitrogen-functionality located at one end of the oligomer chain. The semi-telechelic nitrogen-functionality is believed to allow the nitrogen-functionality to absorb onto the pigment surface without steric hindrance with the pendant polymerizable groups. Further, the oligomer chain containing the pendant ethylenic unsaturations may project away from the pigment surface into the hydrophobic monomers of the medium. These ethylenic unsaturations pendant to the oligomer backbone are unencumbered by the nitrogen-functionality and may readily react with the other monomers in the medium. Further, the method of preparing the semi-telechelic nitrogen-functional oligomers yields oligomers with a single nitrogen-functionality on each oligomer chain.
The first aspect of this invention provides a semi-telechelic nitrogen-functional oligomer with formula:
R1R2Nxe2x80x94(CH2)mxe2x80x94(NH)nxe2x80x94A
where A is the residue of a macromonomer bearing at least one pendant ethylenic unsaturation and where A has a degree of polymerization in the range of 2 to 50, where n is 0 or 1, where m is 0 when n is 0, where m is an integer in the range of 0 to 18 when n is 1, and where R1 and R2 are groups independently selected from the group consisting of H, C1 to C12 branched, unbranched, and cyclic alkyl; phenyl; and substituted phenyl subject to the limitation that only R1 or R2 is H; or where R1R2Nxe2x80x94 is a cyclic group.
The second aspect of this invention provides a method of preparing a semi-telechelic nitrogen-functional oligomer with formula:
R1R2Nxe2x80x94(CH2)mxe2x80x94(NH)nxe2x80x94A
where A is the residue of an macromonomer bearing at least one pendant ethylenic unsaturation and has a degree of polymerization in the range of 2 to 50, where n is 0 or 1, where m is 0 when n is 0, where m is an integer in the range of 0 to 18 when n is 1, and where R1 and R2 are groups independently selected from the group consisting of H, C1 to C12 branched, unbranched, and cyclic alkyl; phenyl; and substituted phenyl subject to the limitation that only R1 or R2 is H, or where R1R2Nxe2x80x94 is a cyclic group; including the steps of preparing a terminally unsaturated precursor macromonomer bearing pendant functional groups, reacting an amine with the terminal unsaturation of the terminally unsaturated precursor macromonomer, and reacting modifiers comprising ethylenic unsaturation with the pendant functional groups.
As used herein, the term xe2x80x9c(meth)acrylatexe2x80x9d denotes both xe2x80x9cacrylatexe2x80x9d and xe2x80x9cmethacrylatexe2x80x9d, the term xe2x80x9c(meth)acrylicxe2x80x9d denotes both xe2x80x9cacrylicxe2x80x9d and xe2x80x9cmethacrylicxe2x80x9d, and the term xe2x80x9c(meth)acrylamidexe2x80x9d denotes both xe2x80x9cacrylamidexe2x80x9d and xe2x80x9cmethacrylamidexe2x80x9d.
As used herein, the term xe2x80x9cpendantxe2x80x9d means that a group, a functional group, or a reactive moiety, is not in the backbone structure of a macromonomer or an oligomer. Further, the reaction of a pendant group for the present invention will not cause any changes of the backbone structure of the macromonomer or oligomer.
The semi-telechelic nitrogen-functional oligomer of this invention is an oligomer with at least one ethylenic unsaturation pendant to the oligomer backbone and with one end of the oligomer terminated by a nitrogen containing group. The ethylenic unsaturation pendant to the oligomer provides a means to incorporate the oligomer into a polymer matrix. The nitrogen functionality provides a functional group which may bond or associate with the surface of a pigment and aid in the dispersion of a pigment. The oligomer of this invention may be represented by formula (I):
R1R2Nxe2x80x94(CH2)mxe2x80x94(NH)nxe2x80x94A.xe2x80x83xe2x80x83(I)
in which A is the residue of a macromonomer with at least one pendant ethylenic unsaturation and the component R1R2Nxe2x80x94(CH2)mxe2x80x94(NH)nrepresents the nitrogen functionality.
The semi-telechelic nitrogen-functional oligomer may be prepared by a general scheme which is summarized below. This general scheme is used to illustrate the invention only. It is not intended to limit the scope of the invention which is defined herein by the specification and the claims. It is also contemplated that some of the steps may be carried out simultaneously or sequentially.
1) Preparation of a terminally unsaturated precursor macromonomer which includes functional groups.
2) Addition of nitrogen functionality to the terminal unsaturation of the precursor macromonomer.
3) Reaction of the functional groups with modifiers including ethylenic unsaturation.
The semi-telechelic nitrogen-functional oligomer may be prepared by first preparing a terminally unsaturated precursor macromonomer, referred to herein as xe2x80x9cprecursor macromonomerxe2x80x9d. The precursor macromonomer includes as polymerized groups the residues of at least one first monomer and at least one second monomer which includes a functional group. The precursor macromonomer is characterized as having an ethylenic unsaturation at one end. The terminal unsaturation may be connected directly to an end monomer residue or may be connected to a linker group, as described herein in formulas (IV) and (V), which is connected to an end monomer residue. In one embodiment, the precursor macromonomer may be represented by the formula (II):
Qxe2x80x94[Y]y[T]zxe2x80x94Hxe2x80x83xe2x80x83(II)
in which Y is the residue of at least one first monomer and T is the residue of at least one second monomer. The individual residues Y and T may be arranged to form alternating, random, or block structures in the precursor macromonomer. The group Q is the terminal unsaturation and optionally, includes a linker group.
The first monomer is an ethylenically unsaturated monomer and may be selected from the group consisting of olefins, styrenes, substituted styrenes, vinyl esters, vinyl ethers, (meth)acrylic acid, alkyl esters of (meth)acrylic acid, hydroxyalkyl esters of (meth)acrylic acid, (meth)acrylamide, N-substituted (meth)acrylamides, methyl vinyl ketone, and mixtures thereof. Preferred monomers include monomers with an xcex1,xcex2-unsaturated carbonyl group such as alkyl esters of (meth)acrylic acid.
Examples of functional groups include halide, hydroxy, hydroxyalkyl, hydroxyaryl, esters of carboxylic acids, aldehyde, ketone, alkylsiloxy, alkoxysilyl, arylsiloxy groups. Suitable second monomers include allyl alcohol, allyl esters such as allyl acetate, vinyl chloride, vinyl bromide, vinyl acetate, vinyl benzoate, C1-C18 alkyl esters of (meth)acrylic acid, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, acrolein, methacrolein, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, allyltrichlorosilane, allyltrimethoxysilane, allyltriethoxysilane, allyltrichlorosilane, y-methacryloxypropyltrimethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, and mixtures thereof. Preferred second monomers include methyl methacrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, and isobornyl (meth)acrylate.
Alternately, the functional group may be generated from a xe2x80x9csecond monomer equivalentxe2x80x9d after the polymerization reaction which prepares the precursor macromonomer. The second monomer equivalent is a monomer which has a group that may be converted to produce the desired functional group after the polymerization reaction is complete or substantially completed during the polymerization reaction. This requires the use of a second monomer equivalent in the polymerization and at least one additional conversion reaction to generate the desired functional group. An example of a second monomer equivalent is vinyl alcohol which does not have a chemically stable monomeric form for use in polymerization reactions. Vinyl acetate may be used as the equivalent monomer for vinyl alcohol. After the polymerization of the vinyl acetate with the first monomer, the precursor macromonomer is subjected to hydrolysis of the acetate group to generate the desired hydroxyl group. Further, the second monomer equivalent may be the same as the first monomer used in the polymerization reaction. For example, vinyl acetate may be used as both the first monomer and the second monomer equivalent to prepare a precursor macromonomer. Partial hydrolysis of the vinyl acetate residues yields a precursor macromonomer with residues of vinyl acetate and vinyl alcohol.
The average compositional range of the precursor macromonomer can vary depending on the choice of first monomer and second monomer, and the desired properties of the semi-telechelic nitrogen-functional oligomer prepared from the precursor macromonomer. A preferred composition range of first monomer to second monomer is 10:1 to 1:10, and a more preferred range is 4:1 to 1:4. The degree of polymerization of the precursor macromonomer is the average number of monomer residues in the precursor macromonomer and is equal to the sum of (y+z) in Formula II. The degree of polymerization may be in the range from 2 to 50, preferably from 3 to 25, and more preferably from 5 to 15. The polydispersity of a mixture of precursor macromonomers may vary over a wide range and may include bimodal or multimodal distributions. A preferred polydispersity is in the range of 1 to 5, preferably in the range of 1 to 3, and more preferably in the range of 1.5 to 3.
The composition and degree of polymerization of the precursor macromonomers can be determined by many conventional analytical techniques such as infrared spectroscopy, gel permeation chromatography (GPC), and NMR. The mole ratio of the monomer residues in the precursor macromonomers can be determined by proton NMR or by gas chromatography of the residual monomers in the unpurified precursor macromonomer sample. The number average molecular weight (Mn) and the weight average molecular weight (Mw) are determined by gel permeation chromatography (GPC) using poly methyl methacrylate molecular weight standards. The average oligomer formula and the degree of polymerization is calculated from the Mn and the mole ratio of monomer residues in the precursor macromonomer. The polydispersity of the precursor macromonomer is the ratio of Mw to Mn.
The precursor macromonomer may be prepared by various polymerization processes known in the art. Anionic polymerization as disclosed in U.S. Pat. No. 4,158,736 and high temperature radical polymerization as disclosed in U.S. Pat. No. 5,710,227 provides a precursor macromonomer represented by formula (III):
H2Cxe2x95x90C(Rxe2x80x2)xe2x80x94[Y]y[T]zxe2x80x94Hxe2x80x83xe2x80x83(III)
in which Rxe2x80x2 represents the pendant group of either the first monomer or the second monomer. For example, for a precursor macromonomer prepared from butyl acrylate as the first monomer and 2-hydroxyethyl acrylate as the second monomer, the Rxe2x80x2 group is either the butyl ester of carboxylic acid or the 2-hydroxyethyl ester of carboxylic acid.
The precursor macromonomer may also be prepared by catalytic chain transfer polymerization with terminally unsaturated macromonomers used as chain transfer agents as described in U.S. Pat. No. 5,362,826. Alternatively, the transition metal complexes may be used to prepare the precursor macromonomer as disclosed in U.S. Pat. No. 5,324,879. The precursor macromonomers prepared by these processes may be represented by formula (IV):
H2Cxe2x95x90C(Rxe2x80x2)xe2x80x94CH2xe2x80x94[Y]y[T]zxe2x80x94Hxe2x80x83xe2x80x83(IV)
in which Rxe2x80x2 represents the pendant group of either the first monomer or the second monomer. In this process, it is preferred that at least one of the monomers used in the preparation of the precursor monomer is an ester of methacrylic acid.
Another process to prepare the precursor macromonomer is conventional radical polymerization using a hydroxy-functional chain transfer agent such as 2-mercaptoethanol. Next a terminal unsaturation is attached by reacting an ethylenically unsaturated monomer with a complementary reactive group which is reactive with the hydroxyl group of the chain transfer agent. Examples of ethylenically unsaturated monomers with a complementary reactive group include glycidyl (meth)acrylate, isocyanatoethyl (meth)acrylate, and (meth)acrylic acid. The ethylenically unsaturated monomers with a complementary reactive group may be attached to the fragment of the hydroxy-functional chain transfer agent by various linkages including ester, urethane, amide, amine, or ether linkages. The precursor macromonomer prepared by this method may be represented by formula (V):
CH2xe2x95x90C(Rxe2x80x3)C(O)xe2x80x94Lxe2x80x94(CH2)pxe2x80x94Sxe2x80x94[Y]y[T]zxe2x80x94Hxe2x80x83xe2x80x83(V)
in which Rxe2x80x3 represents a H or CH3 group, xe2x80x94C(O)xe2x80x94L represents linker groups such as ester, urethane, amide, and ether linkages, and p is an integer in the range of 1 to 20. During the reaction of the hydroxyl group of the chain transfer agent with an ethylenically unsaturated monomer with a complementary reactive group, the residual groups T and Y may not contain hydroxyl groups as these may provide alternate reaction sites for the ethylenically unsaturated monomer with a complementary reactive group. It is preferred that the residual groups T and Y contain pendant groups which are nonreactive to the ethylenically unsaturated monomer with a complementary reactive group.
The precursor macromonomers may be prepared by bulk polymerization, solution polymerization, and emulsion polymerization using batch, semicontinuous, or continuous processes. Preferred methods of preparing the precursor macromonomers are high temperature radical polymerization using a semicontinuous or continuous process, catalytic chain transfer polymerization, and conventional radical polymerization using a hydroxy-functional chain transfer agents.
The precursor macromonomers may be isolated and purified by methods known in the art such as vacuum distillation, rotary evaporation or wiped film distillation to remove solvent and impurities such as residual monomers.
The next step in the preparation of the semi-telechelic nitrogen-functional oligomers of this invention is the introduction of the nitrogen functionality onto one end of the precursor macromonomer to prepare an nitrogen-functional macromonomer. In particular, an amine is reacted with the terminal unsaturation of the precursor macromonomer by various synthetic methods known in the art. A preferred method is conjugate addition of an amine to an activated carbon-carbon bond. Various amines may be used including primary and secondary amines, hydrazines, and diamines. The choice of amine may be determined by the reactivity of the amine towards the terminal unsaturation of the precursor macromonomer and the use of the semi-telechelic nitrogen-functional oligomer in a particular application. For example, primary amines are more reactive towards the terminal unsaturation of the precursor macromonomer than secondary amines.
For the use of the semi-telechelic nitrogen-functional oligomer in the application of dispersing pigments, amines such as tertiary amines with C1 to C4 alkyl groups are effective.
Amines suitable for reaction with the terminal unsaturation include primary amines such as C1 to C12 branched and unbranched alkyl amines, and secondary amines such as dimethylamine. Preferred primary amines include methylamine, n-butylamine, and ethylamine. Other suitable amines include hydrazines such as N,N-dimethyl hydrazine. Further suitable amines include amines of formula (VI):
R1R2Nxe2x80x94(CH2)mxe2x80x94NH2xe2x80x83xe2x80x83(VI)
such as diamines in which R1 and R2 are groups independently selected from the group consisting of H, C1 to C12 branched, unbranched, and cyclic alkyl; phenyl; and substituted phenyl groups and m is an integer with a value in the range of 1 to 18. The diamines of formula (VI) are further limited by the restriction that R1 and R2 are not simultaneously H. Still other suitable amines include nitrogen ring compounds in which the substituent groups R1 and R2 are part of a cyclic group including at least one nitrogen atom. Suitable amines containing a nitrogen ring compound include 4-(2-aminoethyl)morpholine, 1-(2-aminoethyl)piperazine, 4-aminomorpholine, 1-(2-aminoethyl)piperidine, 2-(2-aminoethyl)pyridine, 1-(2-aminoethyl)pyrrolidine, 2-(aminomethyl)pyridine, 3-(aminomethyl)pyridine, 4-(aminomethyl)pyridine, 1-(3-aminopropylimidazole, 4-(3-aminopropyl)morpholine, and 1-(3-aminopropyl)-2-pipecoline. Examples of preferred amines include N,N-dimethyl 1,3-propanediamine, N,N-dimethylethylenediamine, 1-(2-aminoethyl)piperidine, 1-(2-aminoethyl)pyrrolidine, 1-(3-aminopropyl)imidazole, and 4-(3-aminopropyl)morpholine.
A preferred synthetic process to attach the amine onto the terminal unsaturation of the precursor macromonomer is conjugate addition of an amine to an activated carbon-carbon bond such as an xcex1,xcex2-unsaturated carbonyl group. Suitable conditions for this reaction are well known in the art and generally involve heating a mixture containing the amine and the precursor macromonomer and monitoring the progress of the reaction using a suitable analytical technique such as NMR. Suitable reaction conditions are described in W. S. Johnson, E. L. Woroch, and B. G. Buell, Journal of the American Chemical Society, Vol. 71, 1949, pp. 1901-1903 and N. C. Ross and R. Levine, Journal of Organic Chemistry, Vol. 29, 1964, pp 2346-2350.
The semi-telechelic nitrogen-functional oligomer may be prepared from the nitrogen-functional macromonomer by attaching at least one modifier containing an ethylenically unsaturated group onto a functional group of a second monomer residue, thus forming a residue of a monomer bearing a pendant ethylenic unsaturation. The modifier which contains an ethylenically unsaturated group has a complementary functional group which is reactive towards the functional group of the second monomer residue. Suitable modifiers include monomers with complementary functional groups such as (meth)acrylates.
The choice of suitable complementary functional groups to react with the functional group of the second monomer residue are well known in the art. The following reactions between the modifier and the functional group of the second monomer residue are within the scope of the invention whether the functional groups are present on the second monomer prior to the preparation of the precursor macromonomer or generated after the preparation of the precursor macromonomer. Further, the functional groups may be generated after the attachment of the nitrogen functionality.
I. When the functional group is a hydroxy (xe2x80x94OH) group, the complementary functional groups of the modifier may be selected from ethylenically unsaturated carboxylic acids, esters of the ethylenically unsaturated carboxylic acids, acyl halide derivatives of the ethylenically unsaturated carboxylic acids, and mixtures thereof. Examples of a second monomer in this group include allyl alcohol, 2-hydroxyethyl (meth)acrylate, 2-hydroxyethyl crotonate, 3-hydroxypropyl (meth)acrylate, 3-hydroxypropyl crotonate, 4-hydroxybutyl (meth)acrylate, and mixtures thereof. Examples of a second monomer equivalent include allyl acetate, allyl propionate, and vinyl acetate. Examples of a suitable modifier include (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, methacrylic anhydride, citraconic acid, cinnamic acid, methylcinnamic acid, methyl (meth)acrylate, methyl crotonate, ethyl (meth)acrylate, ethyl crotonate, n-propyl (meth)acrylate, n-propyl crotonate, i-propyl (meth)acrylate, i-propyl crotonate, n-butyl (meth)acrylate, n-butyl crotonate, 2-ethylhexyl (meth)acrylate, 2-ethylhexyl crotonate, and mixtures thereof, and acryloyl chloride, methacryloyl chloride, crotonyl chloride, and mixtures thereof.
II. When the functional group is an alkoxysilyl group, the complementary functional groups of the modifier may be selected from hydroxyalkyl esters of ethylenically unsaturated carboxylic acids and mixtures thereof. Examples of a second monomer in this group include vinyltriethoxysilane, vinyltrimethoxysilane, y-methacryloxypropyltrimethoxysilane, vinyltrichlorosilane, allyltriethoxysilane, allyltrichlorosilane, and mixtures thereof. Examples of a suitable modifier include 2-hydroxyethyl (meth)acrylate, 2-hydroxyethyl crotonate, 3-hydroxypropyl (meth)acrylate, 3-hydroxypropyl crotonate, 4-hydroxybutyl (meth)acrylate, 4-hydroxybutyl crotonate, and mixtures thereof.
III. When the functional group is an aldehyde or a ketone, the complementary functional group of the modifier may be a hydroxyalkyl group. Examples of a second monomer are acrolein, methacrolein, methyl vinyl ketone, and mixtures thereof. Examples of a suitable modifier include 2-hydroxyethyl (meth)acrylate, 2-hydroxyethyl crotonate, 3-hydroxypropyl (meth)acrylate, 3-hydroxypropyl crotonate, 4-hydroxybutyl (meth)acrylate, 4-hydroxybutyl crotonate, and mixtures thereof.
The semi-telechelic nitrogen-functional oligomer of this invention may be a liquid or a solid. A preferred form is a liquid with a viscosity less than 10 Pa-s at 25xc2x0 C. to provide easy handling, pouring, and formulation with other materials. A more preferred form is a liquid with a viscosity less than 1 Pa-s at 25xc2x0 C. Alternately, the semi-telechelic nitrogen-functional oligomer may be provided in a solvent medium including haloalkanes such as chloroform; ethers such as ethyl ether; esters such as ethyl acetate; alcohols such as isopropanol and n-butanol; alkanes such as hexane and cyclopentane; ketones such as acetone, amides such as N-methylpyrrolidone; nitriles such as acetonitrile; and aromatics such as toluene.
Other ingredients may be added to the semi-telechelic nitrogen-function oligomer of this invention including polymerization inhibitors such as hydroquinone and p-methoxyphenol; wetting agents; defoamers; antioxidants; and biocides such as fungicides and bactericides. Further, other dispersants may be added to the semi-telechelic nitrogen-functional oligomer to provide dispersant mixtures more effective to disperse specific pigments or mixtures of pigments. In one embodiment, the semi-telechelic nitrogen function oligomer is provided as a dispersion in a medium, preferably a medium containing water, more preferably an organic solvent-free aqueous dispersion. Optionally, surfactants may be used to aid in the preparation of the dispersion and to provide stability to the dispersion.
The semi-telechelic nitrogen-functional oligomer is useful as a dispersant for pigments, particularly in curable formulations such as radiation curable inks and coatings. The pigments may be dispersed by methods well known in the art such as methods described in chapters 17-24 of xe2x80x9cPaint Flow and Pigment Dispersionxe2x80x9d by T. C. Patton, John Wiley Sons, New York, N.Y. (1979). The semi-telechelic nitrogen-functional oligomer may be added to the ink formulation prior to, during, or after the addition of the pigment. Suitable pigments include inorganic pigments such as titanium dioxide, zinc oxide, zinc sulfide, lithopone, lead oxides, iron oxide, bismuth vanadate, chromium(III) pigments, lead chromate, carbon black, and metal pigments; and organic pigments such as pigments listed in Table 1 on pages 42-45 of the xe2x80x9cKirk-Othmer Encyclopedia of Chemical Technologyxe2x80x9d, Volume 19, 4th Edition (1996).
In radiation curable formulations, semi-telechelic nitrogen-functional oligomers containing N-methyl amines and N,N-dimethyl amines are also useful as amine synergists when used in combination with hydrogen abstracting photoinitiators by providing a source of abstractable hydrogen atoms.
As used herein, curable formulations refer to formulations which contain ethylenically unsaturated materials such as monomers and oligomers. In the presence of a suitable initiator, the ethylenically unsaturated materials may undergo reaction to produce a polymer matrix. One example is a radiation curable formulation which contains ethylenically unsaturated monomers such as isobornyl acrylate, trimethylolpropane triacrylate, ethylene glycol diacrylate, and pentaerythritol triacrylate, and a photoinitiator such a benzophenone. Exposure to electromagnetic radiation such a ultraviolet or visible radiation, or electron beam irradiation initiates the reaction of the monomers leading to a polymer matrix. In another embodiment, a curable formulation which contains ethylenically unsaturated monomers and is cured by free radicals generated by chemical or thermal processes is provided.
The semi-telechelic nitrogen-functional oligomer may also be used as a monomer in polymerizations such as emulsion polymerization or as a polymerizable emulsifier. In aqueous emulsion polymerization, the semi-telechelic nitrogen-functional oligomer may provide stability to the emulsion polymer particles. Semi-telechelic nitrogen-functional oligomers with more than one pendant ethylenic unsaturation may be useful as crosslinkers in polymerizations.
In the following Examples, the following abbreviations were used: